A sheet which is subjected to being conveyed in an image forming apparatus is assumed to have a minimum size. A card-sized sheet (hereinafter, referred to as “card”), which has a size smaller than the minimum size, cannot be conveyed in the image forming apparatus. For that reason, in order to form an image on the card by the image forming apparatus, a user needs to attach the card onto a sheet having at least the minimum size capable of being conveyed in the image forming apparatus. After the sheet on which the card is attached is ejected from the image forming apparatus, the card needs to be manually separated by the user.